We are attempting to define the mechanism by which granulocytes consume additional oxygen when they phagocytize and produce increased amounts of O2- and H2O2. The fluoride-induced stimulation of these functions provides a model more easily controlled than phagocytosis per se. The kinetics of the phenomena and the putative participation of a phosphorylation-dephosphorylation cycle of a protein are being studied. The cytochemistry of the oxidase, i.e. the specific locale in the membrane, is under investigation by techniques designed to trap O2-. We are especially interested in ecto-enzymes of this cell type and other phagocytic leukocytes from various species. Attack by such ecto-enzymes on substrates attached to large entities (e.g. Sepharose beads) is followed. The mechanism(s) by which macrophages are activated is another major area of study. We are examining many biochemical characteristics of activated cells and comparing them with control macrophages. In addition, activation of (mouse) macrophages cultured in vitro is being studied, i.e. by exposing them to MIF. Among aspects measured are ecto-enzymes, metabolic rates and particularly, respiratory functions such as those mentioned above for granulocytes. Finally, in attempts to elucidate mechanisms of microbicidal action, changes in bacteria exposed to the myeloperoxidase H2O2-halide system are being explored. BIBLIOGRAPHIC REFERENCES: Curnutte, J.T., Karnovsky, M.L., and Babior, B.M.: Manganese-dependent NADPH oxidation by granulogyte particles. The role of superoxide and the nonphysiological nature of the manganese requirement. J. Clin. Invest. 57: 1059-1067, 1976. Drath, D.B., Harper, A.A., and Karnovsky, M.L.: Biochemical characteristics of alveolar macrophages in LUNG CELLS IN DISEASE. Brook Lodge Conference on Lung Disease Research, Augusta, Michigan, April, 1976. Elsevier/North Holland Publishing Co.